Muti Abdullah, Canbaz Ferda, Tonelli Mauro, Eun Bae Ji, Rotermund Fabian, Petrov Valentin, Sennaroglu Alphan
Opt Lett. 2020 Feb 1;45(3):656-659. doi: 10.1364/OL.385629.
We report experimental demonstration of graphene mode-locked operation of ${{\rm Tm}^{3 + }}!:!{{\rm YLiF}_4}$Tm:YLiF (YLF) and ${{\rm Tm}^{3 + }}!:!{{\rm KY}3}{{\rm F}{10}}$Tm:KYF (KYF) lasers near 2.3 µm. To scale up the intracavity pulse energy, the cavity was extended, and double-end pumping was employed with a continuous-wave, tunable ${{\rm Ti}^{3 + }}!:!{\rm sapphire}$Ti:sapphire laser delivering up to 1 W near 780 nm. The extended ${{\rm Tm}^{3 + }}!:!{\rm KYF}$Tm:KYF laser cavity was purged with dry nitrogen to eliminate pulsing instabilities due to atmospheric absorption lines, but this was not needed in the case of the ${{\rm Tm}^{3 + }}!:!{\rm YLF}$Tm:YLF laser. Once initiated by graphene, stable uninterrupted mode-locked operation could be maintained with both lasers. With the extended cavity ${{\rm Tm}^{3 + }}!:!{\rm YLF}$Tm:YLF laser, 921 fs pulses were generated at a repetition rate of 17.2 MHz at 2304 nm. 739 fs pulses were obtained at the repetition rate of 54 MHz from the ${{\rm Tm}^{3 + }}!:!{\rm KYF}$Tm:KYF laser at 2340 nm. The corresponding pulse energy and peak power were 2.4 nJ and 2.6 kW for the ${{\rm Tm}^{3 + }}!:!{\rm YLF}$Tm:YLF laser, and 1.2 nJ and 1.6 kW for the ${{\rm Tm}^{3 + }}!:!{\rm KYF}$Tm:KYF laser. We foresee that it should be possible to generate shorter pulses at higher pump levels.
我们报告了在2.3 µm附近实现掺铥钇锂氟化物（Tm:YLiF，YLF）和掺铥钇镓氟化物（Tm:KY3F10，KYF）激光器的石墨烯锁模运转的实验演示。为了扩大腔内脉冲能量，扩展了激光腔，并采用连续波、可调谐的掺钛蓝宝石（Ti:sapphire）激光器在780 nm附近提供高达1 W的功率进行双端泵浦。扩展后的Tm:KYF激光腔用干燥氮气吹扫，以消除由于大气吸收线导致的脉冲不稳定性，但Tm:YLF激光器则无需如此。一旦由石墨烯启动，两台激光器都能维持稳定、不间断的锁模运转。对于扩展腔的Tm:YLF激光器，在2304 nm处，以17.2 MHz的重复频率产生了921 fs的脉冲。对于Tm:KYF激光器，在2340 nm处，以54 MHz的重复频率获得了739 fs的脉冲。Tm:YLF激光器对应的脉冲能量和峰值功率分别为2.4 nJ和2.6 kW，Tm:KYF激光器对应的脉冲能量和峰值功率分别为1.2 nJ和1.6 kW。我们预计在更高的泵浦水平下应该能够产生更短的脉冲。
